XP SP1 Breaks Crypto
 

I have encountered a problem with XP. Specifically using
Crypto API after installing the SP1 for XP. There seems
to be an incompatibility between the enhanced provider for
pocket pc and the enhanced provider in that service pack.
If I encrypt something at 128 bits on the Pocket PC, I can
no longer decrypt it on the desktop after installing the
service pack. Everything still works at 40 bit.

The application uses the
Microsoft Enhanced Encryption Provider v1.0, not the
prototype provider that is new to XP with SP1. After
spending a few hours attempting to solve the problem
myself, I found a horrible, nasty, security compromising,
work-around that allows me to use the software.
Thankfully, when installing the service pack, I told it
that I might need to uninstall it later. This allowed me
to recover the original rsaenh.dll file. I then altered
the registry key:
HKLM\software\microsoft\cryptography\defaults\prov ider\Micr
osoft Enhanced Cryptographic Provider v1.0\image path =
path to recovered dll

This fixed the problem immediately after rebooting.
I believe that MS may have introduced a bug in the
Enhanced Provider, however that seems unlikely. I would
appreciate any feedback. Especially a less nasty method
of solving this problem.

Thank you (alot) in advance.